It can be because of dermatitis
or dryness etc. I need details of case n preferably pics of affected area. In the meanwhile follow this
Avoid sudden changes in temperature or humidity.
Avoid scratchy materials, such as wool directly in contact with skin.
Avoid harsh soaps, detergents, and solvents.
Be aware of any foods that may cause an outbreak and avoid those foods.
For this homeopathic treatment is very effective
for more details you can consult me.